How to Reduce Self-Heating in VCSEL Testing

+ Modular PXIe Precision SMU

Reduce Self-Heating During VCSEL Testing

Vertical Cavity Surface Emitting Laser (VCSEL) characterization requires applying a controlled current pulse while measuring the device's electrical and optical response. For narrow-pulse testing, the current pulse must be short enough to limit self-heating while maintaining the required amplitude and rise time. Current and voltage measurements are captured during the pulse to characterize device behavior under the applied operating conditions.

The test measures the actual current and voltage waveforms during the narrow pulse using high-speed sampling. Light output can also be measured through synchronized photodiode current for Light-Current-Voltage (LIV) characterization. The resulting measurements provide the electrical and optical data used to determine characteristics such as forward voltage, threshold current, optical power, photodiode current, and slope efficiency or kink.

Narrow-Pulse VCSEL Test Solution

Narrow-pulse VCSEL testing requires a current source capable of generating short pulses while capturing the device response within the pulse measurement window. The Keysight Precision PXIe Source/Measure Unit (SMU) provides Laser Diode Mode with fast rise time and current pulses as narrow as 10 µs. Embedded high-speed measurement at up to 15 MSa/s captures the actual current pulse and dynamic current and voltage response without requiring an additional waveform-capture instrument. The solution also supports pulsed current sourcing up to 10.5 A, enabling narrow-pulse characterization across a range of VCSEL devices and arrays.

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